1. Field of the Invention
The present invention relates to an image forming apparatus that allows easy fixing of a paper jam, particularly to an image forming apparatus, such as a copier, a facsimile machine, a printer, and the like.
2. Description of Related Art
A conventional image forming apparatus has a paper transport mechanism, as described in Japanese Patent Laid-open Publication Hei 9-216747, that includes: a plurality of rollers, which feed paper for image transfer; and a driving unit, which drives the rollers. FIG. 11 shows meshing of a planetary gear in forward rotation in the driving unit of the conventional paper transport mechanism. FIG. 12 shows meshing of the planetary gear in reverse rotation in the driving unit of the conventional paper transport mechanism.
As shown in FIGS. 11 and 12, driving unit 60 that transmits rotation driving force to the plurality of rollers has planetary gear 61 movable along guide slot 62. When driving motor 63 rotates in a forward direction, planetary gear 61 moves in an R direction along guide slot 62 (FIG. 11) and engages gear 64, so as to rotate and drive gear 64, which transmits the rotation driving force to the rollers, in a paper feed direction. When driving motor 63 rotates in a reverse direction (FIG. 12), planetary gear 61 moves in an S direction along guide slot 62 and disengages gear 64, so as to allow gear 64 to rotate freely. Provided at an engagement and disagreement position of planetary gear 61 and gear 64 is resisting plate 65 and bias spring 66, which allow retention of the position.
It is troublesome to fix a paper jam that occurs in the image forming apparatus since it is required to open a cover of the image forming apparatus, rotate driving motor 63 in the reverse direction for a certain amount, and disengage planetary gear 61 and gear 64 so as to release gear 64 for free rotation.
Further, when the driving unit as described above has a gear that rotates in both forward and reverse directions, instead of the planetary gear, it is required to rotate not only the gear, but also the driving motor and a plurality of gears disposed between the gear and the driving motor, in order to pull out the jammed paper from the image forming apparatus after opening the cover thereof. Therefore, removing the jammed paper requires a substantially large pull force, thus not allowing an operator to easily handle the paper jam.